Heating element



July 12, 1932.

w. R. J. woocK 1,866,785

HEAFEING ELEMENT Filed June 24, 1929 INVENTOR WR. d. made BY QMQLQQLSX;

ATTORN EY Patented July 12, 1932 UNITED STATES PATENT oFFlcE WALTER IB. J. WOOCK, OF LODI, OALIFORNIA, ASSIGNOR TO SUPER MOLD CORPORATION, 0F LODI, GALIFORNIA, .A CORPORATION HEATING ELEMENT Application led .Tune 24,

This invention relates to heating elements and especially to one designed to be used in repairin automobile tires in connection with a melting patch and the usual inflatable air bag, to vulcanize the patch in place in the tire.

The principal object of my invention is to provide a heating unit in the form of a universally flexible pad, adaptedto be placed between the air bag and the patch and having a heating element embedded therein so that the pad and patch with which it is engaged may be heated to the necessary degree to eii'ect the vulcanizing of the patch.

A further object is to provide a heating element for the purpose of such a nature that the necessary heat may be generated there in without danger of damaging the pad material, which will not cut through the padn under the great pressure to which the latter is subjected when in operation, which will follow the bending movements of the pad in any direction without permanent distor- 'tion of the element and which can give rand r extend or contract with the pad without any possibility of damage lbeing done to the 'latter.

AI further object of the invention is to produce a simple and inexpensive device and yet one whlch will be exceedingly eil'ective .for the pose forlwhich it is designed.

These objects I Aaccomplish by means of such structure and relative arrangement of parts as will fully appear` by a perusal of the following specification and claim.

In the drawing similar characters of reference indicate corresponding parts in the sevv eral views:

Fig.l 1 is a cross section of a tire, the heating unit and air bag, arranged in operative relation to vulcanize a patch.

Fig. 2 is a perspective view of the heating unit detached.

Fig. 3 is a fragmentary enlarged longitudinal section of the heating unit.

Fig. 4 isa fragmentary longitudinal elevation of the heating element detached.

Fig. 5 is a fragmentary transverse section of the component parts of a pad show- 1929. Serial N o., 373,114.

ing a modified insulating means for the element wire.

Referring now more particularly to the characters of vreference on the drawing, the pad comprises a, soft rubber member 1 of substantially rectangular shape, and preferably terminating at one end in a reduced neck 2 from which the current conducting cables 3 project.' These cables are connected to the ends of the heating element which is in the form.of a multiple strand wire 4 embedded in the rubber. This wire is arranged as a plurality of longitudinally extending spaced runs or lengths,.connected to each other at alternate ends, to form a fiat coil. The wire itself is of a high grade flexible vspring' allo)7 and from end to end is initially wound in the form of a relatively iat or shallow helical coil of long pitch, as indicated in Fig. 4.

In constructing the pad the wire is preferably first surrounded by an insulating jacket of powdered mica and rubber composition 5, and is laid out in the flat-coil form as above described, on one rubber sheet, another rubber sheet of the same thickness is then superimposed on the coil and the first named sheet and the two are then vulcanized together to completely enclose and embed the element in the finally formed pad, which then forms a single unitary piece.

The insulating composition above described is a special compound of my own of rubber andpowdered mica in nearly equal proportions, and is' especially suitable for this particular'use since it readily vulcanizes or fuses in with the rubber sheets between which it lies. This being the case, it is not necessary that the insulation be an individual jack et about each turn of the wire. Instead it may be prepared in sheet form, in which case the bare wire is laid between two such sheets as at 5a in Fig. 5, and the rubber sheets then engaged with the outer surfaces of said sheets.

The peculiar flat helical form and the ilexible or springy nature of the element enables the same to extend and contract with the surrounding rubber as the latter is placed under pressure; prevents the permanent collapse of the coil Ainder s uch pressure as would occur-if the usual rigid and steep pitch helical element were used; and also prevents the wire cutting into the rubber as the latter is compressed under pressure, since the spring wire, being initially somewhat fiat, will merely flatten out more with such pressure. The

natural resiliency of the wire will bring it back to its normal helical form when this pressure is released. The use of a plurality of strands in the makeup of the wire provides for the desired current carryingl capacity with the use of much smaller and hence more readily flexible wires than would otherwise be the case. The use of a mica jacket about the elements not only helps to insulate the same but by reason of its non-friction charac ter it allows the element to slip freely inside the rubber pad, and thus promotes the ease with which the wire may iatten or elongate as the conditions of heat or pressure may necessitate.

The pad for ordinary use is approximately one foot in length and'of sufficient width to extend substantially three-fourths about the inner periphery of the tire 6. This pad removably rests on or may be formed with or cemented to the outside of the air bag 7 which as usualis inserted in the tire when repairs are to be effected. The heating unit is then of course disposed between the air pad and the patch 8 to be vulcanized. y

The pad being of soft flexible rubber is yieldable in any direction so that one pad may fit in any sized tire. The expense for a complete tire repairing equipment is therefore very much less than that of the ordinary bulky and expensive sets of apparatus at present being necessary; while the heat may be readily controlled to the exact degree necessary for proper vulcanizing Work.

From the foregoing description it.will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claim.

Having thus described my invention what l claim as new and useful and desire to secure by Letters Patent is:

An electric heating unit comprising a universally flexible soft rubber pad, a flexible electric heat-ing wire embedded in the pad, and powdered mica covering said wire from end to end to allow the wire to slip relative to the pad.

ln testimony whereof I aflix my signature.

' WALTER R. J. W OCK. 

